Lubrication

Clean oil is productive oil

The care of your lubricant stock is all about the basics.
By Brad Prickett June 7, 2019
Courtesy: Mobil Industrial Lubricants

When seeking opportunities to increase productivity, many industrial operators turn to bigger ticket items such as new equipment or management techniques.

While these opportunities are important to consider, operators also should be looking at a more fundamental area—their oil. Oil contamination is a serious issue that can harm a plant’s productivity and make it harder for operators to achieve their business goals. Thankfully, managing oil contamination isn’t difficult. It just requires the proper approach to take care of the basics.

To help with this issue, here are some basic guidelines that operators across any industry should follow.

Understanding oil cleanliness

First, what do we mean by oil cleanliness?

Oil cleanliness is the level of particle contaminants in the oil, caused by both external and internal sources. External sources include foreign particles such as dirt or dust, which are abundant in many different types of industrial operations, while internal sources contaminate oil with particles resulting from mechanical wear such as abrasion, fatigue, adhesion and erosion.

To determine the cleanliness of an in-service oil, you must measure the amount of particulate matter within the oil. This can be done through a series of different methods, including ISO 4407, ISO 11500, or ASTM D7647-10. Lubricant suppliers or third-party labs often can conduct these tests. 

Establishing acceptable cleanliness limits

The most important step to maintain proper oil cleanliness is to establish proper targets by component type. To do this, you have to establish acceptable cleanliness limits using the ISO 4406 classification, often referred to as the ISO Cleanliness Code.

The table of recommended Target ISO Cleanliness Codes. Chart information provided by Mobil Industrial Lubricants.

The table of recommended Target ISO Cleanliness Codes. Chart information provided by Mobil Industrial Lubricants.

*Depending upon system volume and severity of operating conditions, a combination of filters with varying degrees of filtration efficiency might be required to achieve and maintain the desired fluid cleanliness.

**Filters are rated according beta ratio 〖(β〗_(x[c]))at specific particles size〖(X〗_μm): β_x[c] =〖n 〗_(upstream ≥ X_μm )/〖n 〗_(downstream ≥ X_μm )

Efficiencies are measured in a multi-pass test, the higher the number the more efficient the filter at a given micron size.

This cleanliness code quantifies particulate contamination levels per milliliter of oil, and is expressed in two or three numbers depending on the particle count method used.

The best way to determine an Oil Cleanliness Code target for a specific piece of equipment is to reference the Table of Recommended Target ISO Cleanliness Codes and selection of media for systems using petroleum-based fluids per ISO 4406, which is shown below. This table helps determine the level of cleanliness required for each application, as well as the filtration required to maintain it.

When using this table as a reference, operators should follow some basic guidelines to ensure the proper targets are selected:

  • Target selection criteria should be based on the most sensitive component in the lubrication system, especially when using a central reservoir to supply multiple systems.
  • If using a non-petroleum-based fluid or water-based lubricant such as water gylcols, use a target ISO Cleanliness Code one value lower than in the table.
  • If equipment operates under frequent cold starts, excessive shock or vibration, or if the component is critical to system reliability, use a target ISO Cleanliness Code two values lower than in the table.

The above guidelines can help ensure that you choose an oil that’s able to maintain the needed level of cleanliness for your application.

But even the best oil can become contaminated if not properly managed.

Maintaining proper oil cleanliness

Keeping oils clean requires following a number of steps throughout the lubricant lifecycle—including proper storage and handling, following lubricant dispensing and filtration best practices, and conducting routine used oil analysis.

Storage and handling: Lubricants become vulnerable to contamination during storage, and especially when handled or moved. Even a sealed container is susceptible to ingress contamination of particles and water as air temperature around the container rises and falls.

In order to reduce contamination during storage:

  • Store lubricants in sealed containers that reside in a sheltered room or building
  • Equip containers with air and water filtration
  • Store drums horizontally
  • Keep large and small bungs in 3 o’clock and 9 o’clock positions, and close bungs promptly after use.

Lubricant dispensing: One of the most important steps in achieving and maintaining oil cleanliness is proper lubricant dispensing. Operators should follow these dispensing and servicing best practices:

  • Always use dedicated pumps, carts and hoses to dispense the lubricant
  • The dispensing pump or cart should be equipped with the appropriate filtering media size and efficiency when filling and topping up oil charges
  • Always clean the filling cap before removing it prior to filling the reservoir
  • Ensure that the oil reservoir is closed (no open cover plate) and the filler cap should always be in place
  • Control oil leakage, as more frequent oil top offs expose the application to greater risk of contaminant ingression.

Filtration: Proper filtration is also an important factor in maintaining oil cleanliness. Filtration involves the use of filters that maintain system cleanliness by removing contaminants that could negatively affect equipment performance—such as water, particulate matter, wear metals, and sludge—from the oil. Operators should work with their OEM, lubricant supplier and other partners to ensure they have the right filters in place.

Implementing routine oil and filter analysis: Perhaps the most important means of ensuring oil cleanliness over the long-term is implementing routine oil and filter analysis.

With used oil analysis (UOA), operators can monitor both equipment and lubricant condition. A regular UOA program allows operators to more effectively monitor cleanliness levels and quickly identify any potential warning signs ahead of equipment failure. UOA will identify trends of abnormal rates of particulate matter in the oil that operators can use to take appropriate action.

Lubrication in a plant setting shouldn’t be taken for granted. In fact, a proper system to ensure oil cleanliness also can extend the life of equipment and improve productivity. Courtesy: Mobil Industrial Lubricants

Lubrication in a plant setting shouldn’t be taken for granted. In fact, a proper system to ensure oil cleanliness also can extend the life of equipment and improve productivity. Courtesy: Mobil Industrial Lubricants

Routine filter analysis is also important, as it analyzes potential contaminants in the filter media. When this data is cross-referenced with UOA results, operators can get a much clearer picture of potential contaminants in the system.

Operators should work with a lubricant supplier or third-party lab to conduct this routine testing, and these partners also can help analyze results and identify actions that need to be taken.

A productive operation starts with a clean system, and lubrication is on the front line of helping keep systems clean. By incorporating the steps outlined above into your maintenance program, you can help enhance equipment life and reduce unscheduled downtime—ultimately helping you improve the productivity, safety and profitability of your business.

In short, to help you deliver on your business goals, don’t forget about the basics.

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Brad Prickett
Author Bio: Brad Prickett, Mobil Industrial Lubricants